fp-ts-errorslisted

# Practical Error Handling with fp-ts This skill teaches you how to handle errors without try/catch spaghetti. No academic jargon - just practical patterns for real problems. ## When to Use This Skill - When you want type-safe error handling in TypeScript - When replacing try/catch with Either and TaskEither patterns - When building APIs or services that need explicit error types - When accumulating multiple validation errors The core idea: **Errors are just data**. Instead of throwing them into the void and hoping someone catches them, return them as values that TypeScript can track. --- ## 1. Stop Throwing Everywhere ### The Problem with Exceptions Exceptions are invisible in your types. They break the contract between functions. ```typescript // What this function signature promises: function getUser(id: string): User // What it actually does: function getUser(id: string): User { if (!id) throw new Error('ID required') const user = db.find(id) if (!user) throw new Error('User not found') return user } // The caller has no idea this can fail const user = getUser(id) // Might explode! ``` You end up with code like this: ```typescript // MESSY: try/catch everywhere function processOrder(orderId: string) { let order try { order = getOrder(orderId) } catch (e) { console.error('Failed to get order') return null } let user try { user = getUser(order.userId) } catch (e) { console.error('Failed to get user') return null